Complexes with Atomic Gold Ions: Efficient Bis-Ligand Formation

• Main Authors: Felix Duensing, Elisabeth Gruber, Paul Martini, Marcelo Goulart, Michael Gatchell, Bilal Rasul, Olof Echt, Fabio Zappa, Masoomeh Mahmoodi-Darian, Paul Scheier
• Format: Article
• Language: English
• Published: MDPI AG 2021-06-01
• Series: Molecules
• Subjects: gold complexes; clusters; ligands; mass spectrometry
• Online Access: https://www.mdpi.com/1420-3049/26/12/3484

Complexes of atomic gold with a variety of ligands have been formed by passing helium nanodroplets (HNDs) through two pickup cells containing gold vapor and the vapor of another dopant, namely a rare gas, a diatomic molecule (H₂, N₂, O₂, I₂, P₂), or various polyatomic molecules (H₂O, CO₂, SF₆, C₆H₆, adamantane, imidazole, dicyclopentadiene, and fullerene). The doped HNDs were irradiated by electrons; ensuing cations were identified in a high-resolution mass spectrometer. Anions were detected for benzene, dicyclopentadiene, and fullerene. For most ligands L, the abundance distribution of AuL<i>_n</i>⁺ versus size <i>n</i> displays a remarkable enhancement at <i>n</i> = 2. The propensity towards bis-ligand formation is attributed to the formation of covalent bonds in Au⁺L₂ which adopt a dumbbell structure, L-Au⁺-L, as previously found for L = Xe and C₆₀. Another interesting observation is the effect of gold on the degree of ionization-induced intramolecular fragmentation. For most systems gold enhances the fragmentation, i.e., intramolecular fragmentation in AuL<i>_n</i>⁺ is larger than in pure L<i>_n</i>⁺. Hydrogen, on the other hand, behaves differently, as intramolecular fragmentation in Au(H₂)<i>_n</i>⁺ is weaker than in pure (H₂)<i>_n</i>⁺ by an order of magnitude.